Non-invasive method and apparatus for treating orthostatic hypotension

ABSTRACT

A non-invasive method and apparatus are provided for treating orthostatic hypotension and for reducing the effects caused there from. An increase in blood and fluid flow in the lower extremities is achieved by vibrating the lower body of the individual at a frequency in the range of 10-120 Hz. The apparatus includes a strap for being secured to a body part of the individual&#39;s lower extremities, e.g., the sole of one&#39;s foot, and a displacement sensor which senses any movement of the body part. The displacement sensor continuously sends signals to a processor of the apparatus which indicate whether there was any movement of the body part. If the displacement sensor did not sense any substantial movement of the body part for a predetermined period of time the processor sends a signal to a vibrating mechanism. The signal activates the vibrating mechanism causing vibration of the body part for increasing blood and fluid flow in the lower extremities. The vibrating mechanism causes vibration for a predetermined period of time.

PRIORITY

This application is based on and claims priority to U.S. ProvisionalApplication No. 60/328,265 filed on Oct. 9, 2001, the contents of whichare incorporated herein by reference.

BACKGROUND

1. Technical Field

This disclosure relates to a medical treatment procedure and apparatusfor performing the same. More particularly, the disclosure relates to anon-invasive method and apparatus for treating orthostatic hypotension.

2. Description of the Related Art

Hypotension is manifested as abnormally low blood pressure. Orthostatichypotension is a condition caused by extended periods of quiet standingor sitting or by sudden changes of position from sitting or lying to asitting or standing position. The effects of orthostatic hypotension aremainly age-dependent and may include high rate of bone loss and muscledegeneration. These effects are primarily attributed to decreases inblood and fluid flow in the lower extremities when the body is in staticupright posture for a prolonged period of time.

It has been shown that the ability of the skeletal muscle pump tocontribute to sustaining blood flow varies considerably as a function ofage and/or physical status. For example, the data on postmenopausalwomen indicate that there are subpopulations of women which do not adaptwell to orthostasis. It has been demonstrated that declining systolicpressure in the absence of any corresponding significant rise indiastolic pressure and/or pulse rate indicates the potential forsignificantly decreased blood flow to the lower extremities for manypostmenopausal women while in an upright position for a prolonged periodof time; a response that is not inconsistent with high rates of boneloss and muscle degeneration.

Current methods of treating orthostatic hypotension include having theindividual wear elastic stockings. The individual is generallyprescribed elastic stockings if his blood pressure drops more than 20mm/Hg while in an upright posture, or the individual manifests obvioussigns of orthostatic hypotension, e.g., fainting.

Accordingly there exists a need for a non-invasive method and apparatusfor treating individuals experiencing orthostatic hypotension,especially individuals in occupational, healthcare, or home settingswhere extended periods of quiet standing or sitting occurs regularly andcould result in significant decreases in bone and muscle loss arisingfrom poor blood circulation and perfusion caused by these staticpostures.

Therefore, it is an aspect of the present disclosure to provide anon-invasive method and apparatus for treating orthostatic hypotensionand for reducing the effects caused from orthostatic hypotension.

SUMMARY

A non-invasive method and apparatus are disclosed for treatingorthostatic hypotension and for reducing the effects caused fromorthostatic hypotension. The non-invasive method and apparatus arecapable of increasing blood and fluid flow in the lower extremities ofan individual while the individual is in a static posture, such as in asitting, standing, or other upright static posture, for a prolongedperiod of time. An increase in blood and fluid flow in the lowerextremities is achieved by vibrating the lower body of the individual ata frequency in the range of 10-120 Hz, and preferably, in the range of40-60 Hz. The acceleration of vibration is more than about 0.1 g/cycleand less than about 1.0 g/cycle (where g=9.8 m/s²), and preferably 0.1g/cycle to 0.2 g/cycle, in order to cause the skin surface to bedepressed by 10-50 microns. The vibration can be uniform, interrupted,varying in magnitude, etc.

The lower body can be vibrated by having the individual rest on avibrating platform, such as described in U.S. Pat. Nos. 5,376,065;5,273,028; 5,190,800; and 5,103,806, the contents of these patents areincorporated herein by reference.

The lower body can also be vibrated by the apparatus of the presentdisclosure. The apparatus enables the individual to be treated fororthostatic hypotension in many settings, such as occupational,healthcare, or home settings where extended periods of quiet standing orsitting occurs regularly. The apparatus includes a strap for beingsecured to a body part of the individual's lower extremity, e.g., thesole of one's foot, and a displacement sensor which senses any movementof the body part.

The displacement sensor continuously sends signals to a processor of theapparatus which indicate whether there was any substantial movement,e.g., more than 10 cm, of the body part. If the displacement sensor didnot sense any substantial movement of the body part for a predeterminedperiod of time, e.g., five minutes, it is determined that the person isin a substantially static posture and the processor sends a signal to avibrating mechanism. The signal activates the vibrating mechanismcausing vibration of the body part to enhance blood and fluid flow inthe lower extremities. The vibrating mechanism could cause vibration ofthe body part for a predetermined period of time, e.g., two minutes totwenty minutes, or until body motion is detected by the displacementsensor.

Controls on the apparatus enable the individual to select and set thepredetermined periods of time and other parameters, such as thefrequency that the vibrating mechanism vibrates, as well as to turn offthe apparatus. The controls can also be used to bypass the automaticactivation of the vibrating mechanism. That is, the controls can be usedto cause direct electrical stimulation of the vibrating mechanism,thereby, bypassing the mechanical displacement sensor, allowing a robustresponse even in the elderly who have lost much, if not most, of theirvibro-tactile sensation abilities. It is provided that the controls canbe located on a wireless or non-wireless remote control for enabling theindividual to easily control the apparatus while in any body position.

It is contemplated for the soles of the feet to be bypassed and theneuromuscular system be stimulated at the level of the Achilles' tendon,triggering skeletal muscle activity. It is further contemplated tostimulate the muscle body itself to directly produce muscle twitching,and therefore, skeletal muscle pump activity.

Potential application of the described method and apparatus isenvisioned in occupational, healthcare, or home settings where extendedperiods of quiet standing or seating is required and which could resultin significant decreases in physical and mental fatigue, as well asother pathophysiological responses associated with decreased blood andfluid flow, including, for example, the disuse related bone and muscleloss arising from the poor perfusion caused by these static postures.

Further features of the above embodiments will become more readilyapparent to those skilled in the art from the following detaileddescription of the apparatus taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments will be described herein below with reference to thedrawings wherein:

FIGS. 1 and 2 are graphs showing the influence of non-vibration andwhole body vibration on several physiologic responses for a young adultfemale;

FIGS. 3 and 4 are graphs showing the influence of non-vibration andwhole body vibration on several physiologic responses for apostmenopausal woman;

FIG. 5 is an isometric view showing a vibrating platform with a patientundergoing vibrational treatment for orthostatic hypotension inaccordance with the method of the present disclosure;

FIGS. 6A-6D are graphs showing the derived cardiovascular parameters asa function of vibration frequency for thirty individuals in the seatedposition;

FIG. 7 is block diagram of an apparatus for treating orthostatichypotension in accordance with the present disclosure; and

FIG. 8 is an enlarged perspective view of a patient's foot configured tobe subject to vibrational treatment for orthostatic hypotension usingthe apparatus of the present disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present disclosure describes a non-invasive method and apparatus fortreating orthostatic hypotension. Once an individual is determined to beexperiencing orthostatic hypotension or that the individual is prone toorthostatic hypotension, the individual can be treated by the method andapparatus of the present disclosure. However, it is understood that theindividual can be treated by the method and apparatus of the presentdisclosure even if there has been no determination made that theindividual is experiencing orthostatic hypotension or is prone toorthostatic hypotension.

Before describing the method and apparatus of the present disclosure, adescription is provided in how to determine whether an individual isexperiencing or likely to experience orthostatic hypotension. Two casestudies are presented below which illustrate the influence of vibratingthe lower extremities on blood flow during orthostatic stress, i.e.,quiet standing, for a young healthy female (age 18) and a postmenopausalfemale (age 46). The individuals were situated on a vibration platform,such as described in U.S. Pat. Nos. 5,376,065; 5,273,028; 5,190,800; and5,103,806, the contents of these patents are incorporated herein byreference. The vibration platform was set to vibrate at 37 Hz, 0.2 g(where g=9.8 m/s²)peak-to-peak vertical whole body vibration.

The studies presented below indicate that vibrating the lowerextremities during orthostatic stress leads to substantial physiologicresponses in the older individual indicative of enhanced blood and fluidflow in the lower extremities, as compared to the physiologic responseswithout vibration, an indication that the older individual isexperiencing orthostatic hypotension. The younger individual does notexperience substantial physiologic responses during vibration ascompared to non-vibration, an indication that vibration seems to helpenhance blood and fluid flow in the lower extremities, but the treatmentis not really necessary for the individual.

The physiologic responses recorded for the two individuals during thestudies include systolic and diastolic blood pressure, as well as pulserate. FIGS. 1-4 illustrate the systolic and diastolic blood pressurechanges, as well as heart rate changes, for the younger and olderindividuals in the standing position (standing began at time zero) withhands held at chest height holding a support 16 (see FIG. 5), followingten minutes in the supine position (first data point).

Upon moving from the supine position to an upright sitting or standing,gravitational forces results in a rapid (on the order of a few minutes)pooling of the blood in the lower extremities. In the absence ofadequate muscle pump activity (i.e., muscle contractions in the legs)systolic blood pressure will fall due to inadequate refilling of theheart. The heart rate will commonly increase to compensate for thedecreased blood volume being pumped per beat, however, this compensationis never complete. Simultaneously, vaso-contraction acts to decrease thevessel volume available for pooling, but this results in an increaseddiastolic pressure. The inability to adequately undertake these normalphysiologic responses to orthostatic stress can have severerepercussions, including dizziness, fainting, muscle fatigue andatrophy, as well as bone atrophy (i.e., osteoporosis), however,essentially everyone experiences some degree of reduced blood and fluidflow during quiet standing and sitting, and therefore, a distinctphysiologic stress.

It is noted that each data point in FIGS. 1-4 represents the average offour replications of the study protocol.

As shown by FIG. 1, without vibration, the younger individual'sphysiologic responses are as follows: following a transient activity,systolic blood pressure begins a slow decrease, consistent with thelower extremity pooling of blood and interstitial fluid. Periodicvaso-constriction results in time-varying diastolic pressures, and heartrate increases slightly. These physiologic responses are indicative ofadequate blood blow to the lower extremities, i.e., these physiologicresponses are inconsistent from those indicative of orthostatichypotension.

With reference to FIG. 2, whole body vibration has a small, but clearlyevident effect on the physiologic response to orthostatic stress in theyoung adult female. The drop in systolic blood pressure is eliminated,and as a result, heart rate is maintained at or below supine levels.Accordingly, the young adult female is not experiencing and is notlikely to experience orthostatic hypotension from maintaining a staticposture.

The response to orthostatic stress in the older individual is decidedlydifferent from that observed in the younger individual. In the case ofthe 46 year old woman, as shown by FIG. 3, systolic blood pressuredecreases substantially on standing, and this is compensated by anabrupt increase in pulse rate. There appears to be little evidence ofany significant increase in diastolic blood pressure suggesting thatperipheral resistance is not increasing, i.e., the individual is lackingboth adequate skeletal muscle pump and vaso-constrictive activity. Thedeclining systolic blood pressure in the absence of any correspondingsignificant rise in diastolic blood pressure and/or pulse rate indicatesthe potential for significantly pooling of blood in the lowerextremities. Accordingly, the older adult female is experiencingorthostatic hypotension from maintaining a static posture.

With reference to FIG. 4, exposure of this woman to vibration results inimprovement in the physiologic response to orthostatic stress. In thepresence of vibration, systolic blood pressure drops negligibly;conversely, diastolic blood pressure increases abruptly and issustained. Pulse rate appears to be undergoing a slow increase over thetwelve minutes of recording.

In accordance with one method of the present disclosure, vibrationapplied to the base of the feet, or whole body vibration, using avibration table 10 as shown by FIG. 5, is sufficient to stimulateneurosensory activity, resulting in a corresponding activation of thereflex arc resulting in sufficient muscle activity to ensure adequateblood and interstitial fluid return to the heart. The effect of thefoot-based vibration, therefore, extends beyond sustaining an adequatenutrient flow to the lower limbs, thereby sustaining nerve, muscle andbone tissue in those regions, but also to upper body and cerebralactivities.

FIG. 5 shows an individual undergoing the treatment method according tothe present disclosure. The individual stands on the vibration table 10.Vibrations, generated by table 10 for a predetermined period of time,for example, 10 minutes, are transmitted through the individual's body.The vibrations are generated by motorized spring mechanisms 12 locatedunderneath a standing platform 14 of the vibration table 10 and attachedthereto. It is contemplated that the vibrations may be generated by aplurality of non-motorized springs or coils attached underneath thestanding platform 14, upon which the standing platform 14 rests.

The frequencies imparted by vibration table 10 are in the range between10-120 Hz with the acceleration of the vibration being in the range of0.1 g/cycle to 1.0 g/cycle (where g=9.8 m/s²), and preferably 0.1g/cycle to 0.2 g/cycle, in order to cause the skin surface to bedepressed by 10-50 microns. Preferably, the frequency of the vibrationtable 10 is in the range of 40-60 Hz. The vibration waves are preferablysinusoidal, however other waveforms are contemplated. The vibration canbe uniform, interrupted, varying in magnitude, etc.

The frequency of vibrational loading of the standing platform 14 can beeasily adjusted to permit focused treatment on specificmechano-receptors in the postural control process, i.e., cutaneousreceptors, golgi tendon organs, muscle spindles, etc. The amplitude ofvibrational loading of the standing platform 14 can be easily controlledfrom 0.05 to 0.5 g.

On the surface of the feet, the dominant sensory systems involve theRuffini corpuscles, the Meisner corpuscles, and the Pacinian corpuscles.In addition, the golgi tendon organs and muscle spindles in the lowerlimbs could play an important role in the sensory transduction process.

Because five different sensory systems may be playing the dominate rolein the detection of foot-based vibration and its influence on skeletalmuscle pump activity, and correspondingly, the cardio-vascular system, aseries of frequency sweep studies were undertaken to characterize thefrequency response characteristics of the physiologic responsesobserved. Because each sensory system manifests distinct frequencyresponse characteristics, this would allow the identification of themost important contributors to skeletal muscle pump control.

Thirty health female volunteers (age 30-80) participated in this study.Each was treated to seven distinct vibration exposures, extending from0-120 Hz, each at 0.2 g (where g=9.8 m/²). Specific treatmentfrequencies included: 0, 15, 22, 44, 60, 84, and 120 Hz. All treatmentswere with the subjects in a seated position with the feet (no shoes)placed on the vibration platform. Exposures were for twenty minutes.Systolic and diastolic blood pressure was taken before and after thevibration treatment. Heart rate was monitored continuously during thetreatment Based on these measurements, four common derivedcardiovascular parameters could be determined: change in the heart-ratepressure product; change in the mean arterial pressure; change incardiac output; and change in left cardiac work.

The results shown by FIGS. 6A-6D clearly demonstrate how low-levelvibration at the feet (with the subject in a seated position) is capableof significantly inhibiting the effects of orthostatic stress. Inaddition, the distinct frequency dependence of the cardiovascularresponse is evident, with the peak sensitivity occurring in the vicinityof 40-60 Hz range for the Mean Arterial Pressure (MAP) and relatedparameters, and in the range of 60-90 Hz for the rate pressure product.In the range of 40-60 Hz, calculations of MAP show that the physiologicresponse to orthostatic stress (upright quiet sitting) can be almostcompletely eliminated by the low level (0.2 g) foot-based vibration.

In these experiments, whole body vibration was utilized as a stimulus,however, as the skeletal muscle pump response does not require wholebody vibration, but only stimulation of the vibration sensory systems inthe lower limbs, it is clear that the apparatus of the presentdisclosure which is described below with reference to FIGS. 7 and 8 canstimulate the vibration sensory systems in the lower limbs, andsubsequently, skeletal muscle pump activity, and can produce a similarresponse.

The main objective or purpose of the apparatus of the present disclosureis to achieve displacements in the range of at least 10 micrometers atthe soles of the feet or other lower extremity body part, in thefrequency range of 10-120 Hz, and preferably, in the range of 40-60 Hz,and that these frequencies be sustained for a predetermined period oftime, e.g., two-minutes to twenty minutes, while the individual is in asubstantially static posture as determined by at least one mechanicaldisplacement sensor.

With reference to FIGS. 7 and 8, the apparatus 100 includes a strapassembly 102 (or other fastening assembly) for being secured to a bodypart of the individual's lower extremity, such as the sole of one's footas shown by FIG. 8, and a displacement sensor 104 which senses anysubstantial movement of the body part. The displacement sensor 104continuously sends signals to a processor 106 of the apparatus 100 whichindicate whether there was any substantial movement, e.g., more than 10cm, of the body part. If the displacement sensor 104 did not sense anysubstantial movement of the body part for a predetermined period oftime, e.g., five minutes, it is determined by the processor 106 that theperson is in a substantially static posture and the processor 106 sendsa vibrating mechanism control signal, VM control signal, to a vibratingmechanism 108.

The VM control signal activates the vibrating mechanism 108 causing atleast one vibration sensor 109 within the vibrating mechanism 108 tovibrate, thereby imparting a vibrational force to the body part forvibrating the body part and resulting in enhanced blood and fluid flowin the lower extremities as described above. The vibrating mechanism 108causes vibration of the body part for a predetermined period of time,e.g., two minutes to twenty minutes, or until body motion is detected bythe displacement sensor 104. The vibration can be uniform, interrupted,varying in magnitude, etc.

After the predetermined period of time, the processor 106 sends acut-off vibrating mechanism signal, VM cut-off signal, to the vibratingmechanism 108 to deactivate the vibrating mechanism 108 to ceasevibration of the body part. The process then repeats itself on aperiodic or irregular basis until the displacement sensor 104 sensesmovement of the body part or the individual uses controls 110 to turnoff the apparatus.

The controls 110 on the apparatus 100 further enable the individual toselect and set the predetermined periods of time and other parameters,such as the frequency that the vibrating mechanism vibrates, as well asto turn off the apparatus 100. The set parameters are transmitted to theprocessor 106 as user control signals. The processor 106 uses the usercontrol signals to control the apparatus 100 according to theuser-selected settings.

The controls 110 can also be used to bypass the automatic activation ofthe vibrating mechanism 108 by the processor 106 transmitting the VMcontrol signal if the displacement sensor 104 does not sense anysubstantial movement within the predetermined period of time. That is,the controls 110 can be used to cause direct electrical stimulation ofthe vibrating mechanism 108, thereby, bypassing the mechanicaldisplacement sensor 104, allowing a robust response even in the elderlywho have lost much, if not most, of their vibro-tactile sensationabilities.

It is provided that the controls 110 can be located on a wireless ornon-wireless remote control for enabling the individual to easilycontrol the apparatus 100 by controlling the operation of the processor106 while in any body position and in any condition. It is furtherprovided that the processor 106 includes a set of programmableinstructions within a storage module which are capable of being executedby the processor 106 for enabling the apparatus 100 to perform itsfunctions. The apparatus 100 further includes a battery compartment (notshown) for placement of a battery 112 therein for powering the variouscomponents of the apparatus 100.

For optimum results, it is noted that two apparatuses, one secured toone lower extremity and other secured to the other lower extremity,operating simultaneously should be utilized.

It is contemplated for the soles of the feet to be bypassed and theneuromuscular system be stimulated at the level of the Achilles' tendon,triggering skeletal muscle activity. It is further contemplated tostimulate the muscle body itself to directly produce muscle twitching,and therefore, skeletal muscle pump activity. Further, it iscontemplated to embody the apparatus within footwear, such as a shoe orsock, for easily placing the apparatus in proximity to the sole of one'sfoot during treatment.

Potential application of the described method and apparatus isenvisioned in occupational, healthcare, or home settings where extendedperiods of quiet standing or seating is required and which could resultin significant decreases in physical and mental fatigue, as well asother pathophysiological responses associated with decreased blood andfluid flow, including, for example, the disuse related bone and muscleloss arising from the poor perfusion caused by these static postures.

The method and apparatus of the present disclosure enable the individualto be treated for orthostatic hypotension in any setting and whileperforming virtually any activity, such as typing and being a passengerin an aircraft, train, automobile, or other vehicle, as well as when theindividual is sleeping or resting. Other advantages provided by themethod and apparatus of the present disclosure is that little or notraining/learning is required of the individuals; the apparatus isinexpensive to construct and its small size and low weight make itconvenient for concealment, storage and use; only a short duration oftreatment is required for significant effect (approximately two minutesper vibrational period); the treatment method using the apparatus can beperformed while the patient is in the standing, seated, or any otherupright static posture; and the apparatus can be used to treat theinfirm elderly where other treatments for orthostatic hypotension arebeyond the physical capabilities of these individuals.

Although this disclosure has been described with respect to preferredembodiments, it will be readily apparent to those having ordinary skillin the art to which it appertains that changes and modifications may bemade thereto without departing from the spirit or scope of thedisclosure.

1. A wearable apparatus for treating orthostatic hypotension, saidapparatus comprising: a vibration mechanism configured for imparting avibrational force to a body part of a lower extremity of an individualduring treatment for a period of time and at at least one frequencysufficient for therapeutic affect on orthostatic hypotension; aprocessing unit for controlling activation of the vibration mechanism inresponse to at least one signal received from a displacement sensor uponsensing non-movement of the body part or from a manually settablecontrol; and a securing mechanism for securing said apparatus to saidbody part, wherein said apparatus is configured and dimensioned forbeing concealed during operation thereof.
 2. The apparatus according toclaim 1, wherein said vibration mechanism is provided below a vibrationplatform for vibrating the vibration platform for the period of time andat the at least one frequency to impart the vibrational force to saidbody part situated on said vibration platform.
 3. The apparatusaccording to claim 1, wherein the period of time is in the range of twoto twenty minutes.
 4. The apparatus according to claim 1, wherein themanually settable control includes means for setting the period of timeand the at least one frequency.
 5. The apparatus according to claim 1,wherein the at least one frequency is in the range of 10-120Hz.
 6. Theapparatus according to claim 1, wherein the at least one frequency is inthe range of 40-60Hz.
 7. The apparatus according to claim 1, furthercomprising a set of programmable instructions configured for executionby the processing unit for activating the vibration mechanism on aperiodic or irregular basis.
 8. The apparatus according to claim 1,further comprising remote control means for remotely controlling saidprocessing unit.
 9. The apparatus according to claim 1, wherein theacceleration of the vibration is in a range of 0.1 g/cycle to 0.2g/cycle to cause the skin surface of the body part to be depressed by10-50 microns.